Bearing assembly



Aug. 11, 5 H. POHLER ETAL BEARING ASSEMBLY 2 Sheets-Sheet 1 OriginalFiled Dec. 9, 1960 United States Patent 3,144,278 BEARING ASSEMBLY HeinzPiihler, Westhofen, Westphalia, and Wolfgang Schmude, Dusseldorf,Germany, assignors to Eisenwerk Rothe Erde G.m.h.I-l., Dortmund, GermanyOriginal application Dec. 9, 19611, Ser. No. 74,864. Divided and thisapplication Nov. 10, 1961, Ser. No. 151,495 Claims priority, applicationGermany Dec. 12, 195% 19 Claims. (Ci. 3tl815) The present inventionrelates to bearings.

This application is a division of our copending application Serial No.74,864, filed December 9, 1960, entitled Ball Bearing and Process forManufacturing Races Therefor.

More particularly, the present invention relates to ball bearings ofextremely large diameter, on the order of one meter or more. In bearingsof this type the races are not only made up of annular bodies of metalsuch as steel, but in addition these annular bodies carry wire rings ofsteel which are directly engaged by the balls of the bearings so thatthese balls roll on the wire rings which are carried by the annularbodies of the races.

A particular problem resides in providing bearings of this type withsuflicient stiffness and rigidity as well as with the desired amount ofaccuracy, and also because of the large size these hearings areunusually heavy which is a further disadvantage.

It is therefore one of the primary objects of the present invention toprovide a bearing of the above type which is very light in weight,particularly as compared to conventional bearings of the above type.

The lightness in the weight of the bearing of the invention is broughtabout by using a light metal alloy for the annular bodies of the raceswhich carry the wire rings which are directly engaged by the ballmembers. Particular problems arise when dealing with such light metals.In the treatment of these light metals there are certain residualinternal stresses which make it very difficult to machine such materialsaccurately. Furthermore when a bearing race of light metal is connectedto a support of a metal such as steel or the like, particular problemsarise because of the different coeflicients of thermal expansion so thatwhen the temperature changes the light metal will expand or contract toa degree greater than the steel support, and measures must be taken tocompensate for these different rates of expansion and contractionresulting from temperature changes.

A further object of the present invention is to provide a light metalbearing race which will have a very great strength far beyond thestrength which is conventionally expected of elements made from lightmetals.

An additional object of the present invention is to provide a means forconnecting light metal bearing races to a support in such a way that thedifferent rates of expansion and contraction of the light metal bearingrace and the support to which it is connected can be compensated forwithout in any way disturbing the operation of the bearing.

In accordance with the present invention there is provided, in a bearingassembly, a light metal bearing race and a support for this race, thesupport having a coefficient of thermal expansion which is substantiallysmaller than that of the race. A connecting means connects the race tothe support so that the race is carried by the support, and thisconnecting means of the invention connects the race to the support forlimited movement with respect thereto So that during temperature changesthe race can move with respect to the support to compensate for thedilferent rates of expansion and contraction of the support and raceresulting from temperature changes.

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The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings, inwhich:

FIG. 1 is an axial section through one side of one embodiment of abearing according to the present invention;

FIG. 2 is an axial section through one side of a bearing of theinvention illustrating the structure of the invention for connecting thebearing to a support made of a metal different from the light metal ofthe bearing races; and

FIG. 3 is a fragmentary axial section through one side of a bearing ofthe invention illustrating another embodiment of a structure forconnecting the light metal bearing to a support of steel or the like.

Referring now to FIG. 1 there is illustrated therein a bearing of theinvention. This bearing includes an inner ring 1 forming the inner raceof the bearing. It is to be understood that while the member 1 isreferred to as the inner bearing race because the member 1 is made of alight metal alloy it actually does not engage the balls 4- and carrieswire rings of steel or the like for this purpose. The inner bearing race1 is of a substantially T- shaped cross section with the leg of the Textending horizontally and the cross bar of the T extending verticallyas indicated in FIG. 1 so that the race 1 includes an outer annularflange. This flange is received within the outer race means of thebearing, and this outer race means is formed by a pair of races 2 and 3,the race 2 being located over the race 3 and both of these races havingan angular cross section, as indicated in FIG. 1. The particular bearingillustrated in FIG. 1 includes two series of ball members 4, and eachcircular row of balls 4 engages four wire rings of steel or the likewhich are directly carried by the races 1-3 in the manner shown in FIG.1 where the wire rings 5 are illustrated. Such wire rings 5 are wellknown in the art and therefore are not further described. Each circularrow of balls cooperates with a cage 6 which is also conventional andwhich is formed with a series of openings in which the balls 4 arerespectively located, as is well known.

The bearing which is illustrated in FIG. 1 does not differ in its outerconfiguration and in its load-carrying capacity from conventional wirerace bearings where the wire rings are carried in steel races. Accordingto the invention the races 1-3 are made of a light metal alloy withoutsacrificing precision and at the same time gaining the great advantageof a great reduction in weight.

In one example of the invention the alloy is composed of aluminum, zinc,magnesium and copper, and the copper is present in the alloy in theamount of from 0.5 to 1.5%.

As has been indicated above because the bearing races of the inventionare made of a light metal alloy which has a relatively high coefficientof thermal expansion, particular problems arise when mounting theseraces on supports of metal such as steel which have a much lowercoefficient of thermal expansion. The present invention provides also asolution to the problem of mounting bearings of light metal alloy onsuch supports in such a way as to take care of the problem arising fromthe difierent degrees of expansion and contraction resulting fromtemperature changes.

Thus, referring to FIG. 2, it will be seen that the outer races 2 and 3of the bearing of FIG. 1 are formed with aligned bores which receive thescrew 21. This screw 21 extends through an aligned bore formed in asupport 23 made of steel, for example. The screw 21 is provided at itslower end with a portion 22 which has a tight fit in the bore of thesupport 23, and the opposite end portion of the screw 21 adjacent to itshead is provided with a portion 24 which has a tight fit in the bore ofthe race 2 which with the race 3 forms the light metal race means of theembodiment of FIGS. 1 and 2. In accordance with the present inventionthe screw 21 has a shank portion 25 of reduced diameter as compared tothe portions 22 and 24 between which the shank portion 25 extends, andas a result the screw 21 extends with substantial clearance through thebore of the race 3 which is aligned with the bore of the support 23.Thus, this screw 21 together with the portions of the support 23 andrace means 2, 3 provided with the aligned bores through which the screw21 extends forms a connecting means which connects the race means to thesupport 23, and this connecting means enables the race means to have alimited degree of movement with respect to the support 23 to compensatefor different rates of expanison and contraction resulting fromtemperature changes. When there is an increase in temperature thehearing will of course tend to expand to a degree greater than thesupport 23, and because of the portions 22 and 24 of the screw 21 whichhave a tight fit the expansion of the bearing with respect to thesupport will result in a slight bending or curving of the shank portion25 so that this shank portion 25 will have a substantially S-shapedconfiguration. It is easily possible for the screw 21 to assume thiscurvature inasmuch as the shank portion 25 is relatively long. Ofcourse, there are several screws 21 distributed about the common axis ofthe bearing and its support, with the result that when the temperatureagain falls the screws will resiliently move back to their originalstraight condition and in so doing will center the bearing with respectto the support, so that in this way the structure of FIG. 2 guaranteesthat the bearing will at all times remain precisely centered. Of course,the screws 21 are uniformly distributed about the axis of the hearing soas to have this centering effect.

The inner race 1 is connected to the support 29 in the same way that theouter race means 2, 3 is connected to the support 23. Thus, the race 1is formed with an axial bore aligned with a bore of the inner flange ofthe support 29, and the screw 26 has portions 27 and 28 which have atight fit in the bores of the race 1 and the support 29. Between itstight-fitting portions 27 and 28 the screw 26 has a shank 26a of reduceddiameter to provide the clearance shown in FIG. 2, and this clearancewill enable shifting of the race 1 with respect to the support 29 tocompensate for different rates of expansion and contraction resultingfrom temperature changes in the same way as described above inconnection with the screw 21. Thus, the shank 26a will assume asubstantially S-shaped configuration resulting from expansion due to atemperature increase, and inasmuch as a plurality of the screws 26 areuniformly distributed about the axis of the bearing these screws 26 willhave also a centering influence when the temperature drops.

The bearing shown in FIG. 3 includes only one series of ball membersalthough the supporting arrangement of FIG. 3 may be used equally wellwith a bearing having two series of ball members. The steel supportmembers 36 and 39 are provided to carry the bearing structure of FIG. 3.The support 36 has a flange which is provided with a frustoconicalsurface 44 while the support 39 has a flange provided with thefrustoconical surface 45. The bearing of FIG. 3 includes the light metalalloy rings 37 and 41 which together form the outer race means of thehearing, it being understood that the bearing includes the circular wiremembers which are directly engaged by the bail members and which arecarried by the light metal alloy race members. A screw 40 is shown inFIG. 3 holding the outer race rings 41 and 42 together and of course aplurality of such screws 40 are provided and are uniformly distributedabout the axis of the bearing so as to form a single assembly from theouter light metal alloy rings 41 and 42, and in this way the outerbearing race means 37 is formed. An annular shim 43 whose thickness maybe selected in a well known manner is provided between the rings 41 and42 so as to very accurately determine the cooperation of the races 41and 42 with the ball members. The bearing also includes the inner race30 made of light metal alloy, and it will be noted that the inner race30 has an outer frustoconical surface of the same conicity as andengaging the frustoconical surface 44 of the support 36 in the mannerindicated in FIG. 3. In the same Way the ring 42 has an outer beveledperiphery of the same conicity as and engaging the frustoconical surface45 of the support 39. These engaging frustoconical surfaces function aspart of the connecting means for connecting the light metal alloybearing to the support structure which is made of a metal having acoefficient of expansion substantially smaller than that of the lightmetal used for the bearing races.

In accordance with the invention a pair of rings 32 are respectivelyfixed by the screws 31 to the rings 42 and 30, and it will be seen thateach of the rings 32, which are also made of light metal alloy, has anouter flange overlapping the face of the flange of the support 36 or 39which is directed away from the frustoconical surface 44 or 45 thereof,respectively. Thus, it will be seen that the flange 33 of the upper ring32 of FIG. 3 overlaps the face 35 of the flange of the support 36, thisface 35 being directed away from the frustoconical surface 44, while theouter flange of the lower ring 32 overlaps the face 38 of the flange ofthe support 39, and this latter face 38 is directed away from thefrustoconical surface 45. While the faces 35 and 38 are overlapped bythe flanges of the rings 32, these flanges are nevertheless spaced fromthe faces 35 and 38, respectively, and at the faces which are directedtoward the faces 35 and 38 the flanges of the rings 32 are respectivelyformed with recesses which receive the coil springs 34 which are undercompression, and these coil springs respectively press against the faces35 and 38. Thus, the coil springs 34 act as a spring means urging thepairs of frustoconical surfaces together, and in this way the springmeans together with the flanges of the supports and rings 32 as well astogether with the frustoconical surfaces form a connecting meansconnecting the bearing of FIG. 3 to the support for limited movementwith respect thereto to compensate for different rates of expansion andcontraction resulting from temperature changes. It will be noted thatduring contraction and expansion resulting from temperature changes aslight degree of axial movement of the hearing will take place withrespect to the support, and the springs 34 serve to yield in order tocompensate for this slight axial movement.

When the bearing structure of FIG. 3 becomes heated the light metalalloy rings will expand at approximately twice the rate of the steelrings and thus the rings 30 and 42 will respectively slide along thesurfaces 44 and 45. This sliding takes place by overcoming the frictionresulting from the compression of the springs 34 as well as from theeffective weight of the bearing itself. Assuming that one of the supportrings such as the ring 39 is fixed to the frame of the machine then thering 36 will shift axially during breathing of the frustoconicalsurfaces so as to compensate for axial and radial expansion of the lightmetal alloy bearing. Inasmuch as the expansion is extremely small inrelation to the diameter of the frustoconical surfaces, there is nodanger that the bearing will tilt between the steel support rings. Thepairs of cooperating frustoconical surfaces always lie flush one againstthe other and the inclination of the frustoconical surfaces is notself-locking so that when the bearing cools the return of the parts bythe springs 34 is assured.

The light metal alloy for the ring to be taken consists of an alloy withthe following alloy ingredients in percent: 2.5-5% copper, 0.2-l.8%magnesium, 0.3-1.5% Mangan, rest aluminium. These alloys are naturallyaging. Particularly, an alloy with the following ingredients in per centis to be taken: 3.85.2% zinc, 2.43.8% magnesium, 05-15% copper, restaluminium. This alloy is aging artificially.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofbearings differing from the types described above.

While the invention has been illustrated and described as embodied inlight metal bearings, it is not intended to be limited to the detailsshown, since various modifications and structural changes may be madewithout departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended with-in the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a bearing assembly, in combination, a light metal alloy bearingrace; a support for said race, said support having a coefficient ofthermal expansion substantially smaller than that of said race; andconnecting means connecting said race to said support so that said raceis carried by said support, said connecting means connecting said raceto said support for limited movement with respect to said support sothat during temperature changes said race can move with respect to saidsupport to compensate for the different rates of expansion andcontraction of said support and race resulting from temperature changes,said connecting means including a resiliently deformable portion andbeing arranged in such a manner that, when said race moves relative tosaid support under the influence of temperature changes, said portion isresiliently deformed so as to exert a resilient force tending tomaintain the relative position of race and support during anytemperature change.

2. In a bearing assembly, in combination, light metal alloy bearing racemeans; support means for said race means, said support means having acoefficient of thermal expansion substantially less than that of saidrace means, and said support means and race means contacting each otherand having their contacting portions formed with aligned borescommunicating with each other; and a screw extending through saidaligned bores for connecting said race means to said support means, saidscrew having at one end portion a tight fit in said bore of said supportmeans and at an opposite end portion a tight fit in said bore of saidrace means, and said screw having an elongated shank portion of reduceddiameter between said end portions so that said shank has a substantialclearance in said bore of said race means permitting resilient bendingof said screw along its shank portion of reduced diameter duringshifting of said race means with respect to said support means resultingfrom temperature changes.

3. In a bearing assembly, in combination, a light metal alloy bearingrace; a support for said race, said support having a coefficient ofthermal expansion substantially smaller than that of said race; andconnecting means connecting said race to said support so that said raceis carried by said support, said connecting means connecting said raceto said support for limited movement with respect to said support sothat during temperature changes said race can move with respect to saidsupport to compensate for the different rates of expansion andcontraction of said support and race resulting from temperature changes,said connecting means including a pair of frustoconical surfaces of saidrace and support engaging each other and having the same conicity sothat said frustoconical surfaces can slide one with respect to the other6 and said connecting means connecting said race and support to eachother for limited axial movement one with respect to the other, and saidconnecting means including a spring means urging said frustoconicalsurfaces toward each other.

4. In a bearing assembly, in combination, a support having a flangeformed with a frustoconical surface; light metal alloy bearing racemeans formed with an annular cutout receiving said flange, said racemeans having a frustoconical surface of the same conicity as saidfrustoconical surface of said support engaging said frustoconicalsurface of said support and said support having a face directed awayfrom its frustoconical surface, said race means having a flangeoverlapping and spaced from said face of said support and provided witha face directed toward said face of said support, at least one of saidfaces being formed with a recess; and spring means located between saidfaces and extending into said recess for urging said frustoconicalsurfaces toward each other, said support having a coefiicient of thermalexpansion substantially smaller than that of said race means so that thelatter can shift at its frustoconical surface with respect to saidsupport while having a slight degree of axial movement with respectthereto.

5. In a bearing assembly, in combination, a support having a flangeformed with a frustoconical surface; light metal alloy bearing racemeans formed with an annular cutout receiving said flange, said racemeans having a frustoconical surface of the same conicity as saidfrustoconical surface of said support engaging said frustoconicalsurface of said support and said support having a face directed awayfrom its frustoconical surface, said race means having a flangeoverlapping and spaced from said face of said support and provided witha face directed toward said face of said support, at least one of saidfaces being formed with a recess; and spring means located between saidfaces and extending into said recess for urging said frustoconcialsurfaces toward each other, said support having a coeflicient of thermalexpansion substantially smaller than that of said race means so that thelatter can shift at its frustoconical surface with respect to saidsupport while having a slight degree of axial movement with respectthereto, said race means including a pair of rings one of which isprovided with the frustoconical surface of said race means and the otherof which has the flange of said race means, and fastening membersinterconnecting said rings of said race means.

6. In a bearing assembly, in combination, a race ring; an annularsupport for said race ring coaxially arranged therewith and having acoefficient of thermal expansion substantially smaller than that of saidrace ring; and connecting means connecting said race ring to saidannular support so that said race ring is carried by said support forlimited movement with respect thereto so that during temperature changessaid race ring can move with respect to said support to compensate forthe different rates of expansion and contraction of said support andrace ring resulting from temperature changes, said connecting meansengaging said race ring at portions thereof distributed about the axisthereof and said connecting means including a resiliently deformableportion and being arranged in such a manner that, when said race ringmoves relative to said support under the influence of temperaturechanges so as to exert a resilient force tending to maintain the coaxialrelationship of said race ring and support during any temperaturechanges.

7. In a bearing assembly, in combination, bearing race means; supportmeans for said bearing race means, said support means having acoefiicient of thermal expansion substantially less than that of saidbearing race means; and connecting means connecting said bearing racemeans to said support means for limited movement with respect theretoand so that during temperature changes said bearing race means can movewith respect to said support means to compensate for the different ratesof expansion and contraction of said support means and said bearing racemeans resulting from temperature changes, said connecting meansincluding an elongated member having a pair of end portions fixedly andimmovably connected to said support means and said bearing race means,respectively, and having intermediate said end portions an elongatedresiliently deformable portion integral with said end portions andradially spaced from said bearing race means and support means and beingdeformed during different rates of thermal expansion and contraction ofsaid support means and said race means so as to exert onto the: latterradial forces tending to maintain the relative position of race meansand support means during any temperature change.

8. In a bearing assembly, in combination, bearing race means; supportmeans for said bearing race means, said support means having acoefficient of thermal expansion substantially less than that of saidbearing race means, said support means and said race means being formedwith aligned bores extending in axial direction of said race means; andconnecting means connecting said bearing race means to said supportmeans so that said bearing race means is carried by said support meansfor limited movement with respect thereto and so that during temperaturechanges said bearing race means can move with respect to said supportmeans to compensate for the different rates of expansion and contractionof said support means and said bearing race means resulting fromtemperature changes, said connecting means including an elongatedrod-shaped member having a pair of end portions respectively tightlyfitted into said bores of said support means and said race means andhaving intermediate said end portions an elongated resilientlydeformable portion integral with said end portions and radially spacedfrom said bearing race means and support means and being deformed duringdiflerent rates of thermal expansion and contraction of said supportmeans and said race means so as to exert onto the latter radial forcestend- .ing to maintain the relative position of race means and supportmeans during any temperature change.

9. In a bearing assembly, in combination, a bearing race; and supportmeans having a coefficient of thermal expansion substantially smallerthan that of said race, said support means supporting said raceimmovably in axial direction while permitting limited movement of saidrace in radial direction relative to said support means so that duringtemperature changes said race can move with respect to said supportmeans to compensate for the different rates of expansion and contractionof said support means and race resulting from temperature changes, saidsupport means including biasing means which are stressed duringdifferent expansion and contraction of race and support means so as toexert radial forces on said race tending to maintain the relativeposition of race and support means during any temperature change.

10. A bearing assembly as set forth in claim 9 in which said bearingrace is made from light metal alloy.

References Cited in the file of this patent UNITED STATES PATENTS2,724,621 Kenney Nov. 22, 1955 72,785,934 Alderstam et a1 Mar. 19, 19573,002,429 Franke et a1 Oct. 3, 1961 FOREIGN PATENTS 560,923 France July23, 1923 1,041,307 Germany Oct. 16, 1958

1. IN A BEARING ASSEMBLY, IN COMBINATION, A LIGHT METAL ALLOY BEARINGRACE; A SUPPORT FOR SAID RACE, SAID SUPPORT HAVING A COEFFICIENT OFTHERMAL EXPANSION SUBSTANTIALLY SMALLER THAN THAT OF SAID RACE; ANDCONNECTING MEANS CONNECTING SAID RACE TO SAID SUPPORT SO THAT SAID RACEIS CARRIED BY SAID SUPPORT, SAID CONNECTING MEANS CONNECTING SAID RACETO SAID SUPPORT FOR LIMITED MOVEMENT WITH RESPECT TO SAID SUPPORT SOTHAT DURING TEMPERATURE CHANGES SAID RACE CAN MOVE WITH RESPECT TO SAIDSUPPORT TO COMPENSATE FOR THE DIFFERENT RATES OF EXPANSION ANDCONTRACTION OF SAID SUPPORT AND RACE RESULTING FROM TEMPERATURE CHANGES,SAID CONNECTING MEANS INCLUDING A RESILIENTLY DEFORMABLE PORTION ANDBEING ARRANGED IN SUCH A MANNER THAT, WHEN SAID RACE MOVES RELATIVE TOSAID SUPPORT UNDER THE INFLUENCE OF TEMPERATURE CHANGES, SAID PORTION ISRESILIENTLY DEFORMED SO AS TO EXERT A RESILIENT FORCE TENDING TOMAINTAIN THE RELATIVE POSITION OF RACE AND SUPPORT DURING ANYTEMPERATURE CHANGE.